A TWIN STUDY OF SCHIZOPHRENIA, BIPOLAR DISORDER AND DEPRESSION AT THE INSTITUTE OF PSYCHIATRY, KING’S COLLEGE LONDON
www.iop.kcl.ac.uk/twinstudy
You and your twin are being asked to take part in a research study. Before you decide, it is important that you understand why the research is being done and what it will involve. Please take the time to read the following information carefully and discuss it with your twin, family or GP. Please ask us if anything is unclear or if you would like more information. Take time to decide whether or not you want to take part. Thank you for reading this.
1 Who are we looking for?
Twins between 16 and 60 years of age. You can be identical or non-identical. Our study cannot be complete unless both types are included. You may or may not have a diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder or depression. If you do, you can help us study the characteristics we are interested in. If you don’t, you can help us establish what happens on a behavioural level when these characteristics are absent.
2 Why are we doing this study?
We are interested in finding out more about the genetic and environmental causes and triggers of schizophrenia, bipolar disorder and depression. The term ‘schizophrenia’ refers to a mental illness characterised by hallucinations, thought disorder, delusions, and negative symptoms such as lack of affect and social withdrawal. The term ‘bipolar disorder’ refers to a spectrum of mood disorders that are primarily characterised by a dys-regulation of mood. The term ‘depression’ is referred to as a mental state characterized by a pessimistic sense of inadequacy and a despondent lack of activity
3 Why are twins important to the study?
We now know that some of the factors involved in the development of schizophrenia, bipolar disorder and depression are genetic (e.g. predisposing genes), while others are environmental (e.g. stressful life events, or obstetric complications). We also know that some, but not all, patients with schizophrenia, bipolar disorder and depression present with subtle brain or cognitive abnormalities, which may be related to the clinical symptoms.
What we do not know is the extent to which the various abnormalities are genetically inherited, caused by some early environmental insult (e.g. obstetric complications), or result from a process that begins near the onset of the illness and may, or may not, progress with subsequent episodes.
Twin studies are very powerful for untangling genetic, environmental and disease-related influences on brain function and behaviour. Identical twins share 100% of their genetic make-up, while non-identical twins share only 50%. Therefore, if a characteristic is more similar within identical twin pairs than within non-identical twin pairs, we can infer a genetic influence on it. If not, external factors, such as stressful life events or disease-related parameters (e.g. medication), are more likely to play a role.
Knowing the main causes of abnormal behaviour is very important. If they are environmental or disease-related, we may take practical steps to reduce the impact of the causes involved. Knowing which abnormalities are genetically determined, on the other hand, can help genetic studies narrow down their search for predisposing genes.
4 What happens during the study?
You will be asked to complete some questionnaires, and undergo a clinical interview, neuropsychological tasks, a zygosity test, an EEG test and/or a brain scan. If you do agree to come and be seen at the Institute, we will arrange and pay for all your travel and, if necessary, accommodation, costs. In addition we will reimburse with a payment to you to thank you for your time.
Clinical Interview
These are standard medical interviews. You will be asked about your past medical history and how any psychological symptoms developed. This interview lasts about one hour.
Questionnaires
We will ask you to complete a series of questionnaires that include some questions regarding demographic information and how you generally feel.
Neuropsychological tasks
Some of these consist of answering questions and solving simple problems. Others consist of completing simple tasks on a computer. You do not require any computer skills to participate in the computer sessions.
Zygosity test
As you know, there are both identical and non identical twins. The only way to establish accurately what sort of twin you are, is to take a blood test or, if you don’t like needles, a mouth swab from both you and your twin. We will then check the samples to establish if the genetic material is identical. Once we take a sample, we will store it under a code number, which protects your identity. Ethical Committee panels (special independent bodies) carefully supervise the storage of genetic samples.
EEG and Evoked Related Potentials Tests (ERP)
This test involves measuring the electrical waves that take place naturally in the brain using a well known technique called EEG (electroencephalogram). EEG and Evoked Potential recordings provide a safe way of looking at the brain’s activity. It is like an ECG test for the heart, only in this case leads are attached to the head instead of the chest. This test can not hurt you in any way and it does not use any radiation. Whilst doing the EEG test you will be asked to complete a few simple tasks. One task involves listening to tones through earphones and responding only to the tone with a higher pitch. This test lasts about 90 minutes.
Brain (MRI) scan
This involves lying in a magnetic resonance imaging (MRI) scanner. Pictures of the brain will be taken using a magnetic field. This is a safe and reliable method to obtain pictures, which uses no radiation, and is frequently used in the National Health System. You will have a chance to lay in the scanner before we start our tests to make sure that you are comfortable with the position. There is a microphone in the scanner and you can let us know if anything is wrong. Whilst in the scanner, you will be asked to complete some simple tasks, e.g. reading words from a screen.
5 Confidentiality
The results of the tests are confidential and are protected by the Data Protection Act. Any information that we collect and that leaves the Institute will have your name removed from it so that you can not be recognised from it. If during the course of this project we obtain information that will be clinically important, we will seek your approval to contact your GP or your Consultant Psychiatrist. In view of this, we need your agreement to these arrangements. When the results of the study are available, we will publish them in the medical literature. We will not use any names and no individuals will be recognisable.
6 Frequently asked questions
How much of my time will the study take?
Your participation will be completed after 1 or 2 interviews (these can be conducted over the phone, or sometimes in person), 1 or 2 visits at the Institute of Psychiatry (each will take 3-5 hours including a lunch break), and the completion of some questionnaires at your leisure.
Will I get paid?
Yes
Where will the study take place?
At the Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF. The nearest railway station is Denmark Hill, 5 minutes walk from the Institute. Alternatively, if you are not able, you can complete most of the study from your home. However, the brain scan can only take place at the Institute.
I am working full time. Can I still participate?
Yes. The interviews and questionnaires can be carried out in your free time, and one or both of your visits can take place on a Saturday or Sunday.
Will every twin who wishes to participate finally take part in the study?
No. Our study has a target number of volunteers and we will stop when we have reached this target. Normally, we invite twins to participate if their co-twin can commit to the study as well, although exceptions do apply. Twins with a first language other than English will not complete the neuropsychological tasks (even if their English is excellent!), and usually we prefer volunteers who can complete the full protocol of the study.
When will I know if I can take part?
If you or your co-twin have a diagnosis of schizophrenia, bipolar disorder or depression, you are almost certain to participate in at least one component of our study, if you decide to. If neither of you have schizophrenia, bipolar disorder or depression, you will know if you can participate as soon as we have conducted the two interviews with you. The first one is brief (10-15 minutes) and will help us to obtain some background information (e.g. age, gender, profession). The second interview may last for up to one hour and will help us to obtain some information about your current and past physical and emotional health. Both interviews are confidential, are conducted by trained professionals, and it is best if they take place in a quiet and private setting. We will be happy to conduct them in person if you prefer that option.
How soon can I participate?
Usually you can participate immediately. However, sometimes we will ask for your permission to contact you in a few months’ time to inquire if you are still interested in participating. This may happen for several reasons. For example, if you suffer from schizophrenia bipolar disorder or depression, you may want to wait until you are well enough to participate. If you do not suffer from schizophrenia, bipolar disorder or depression, we may want to wait until we have a volunteer with schizophrenia, bipolar disorder or depression who has similar age, gender and education as you. This is very important. Unless our different groups are similar in every respect apart from the disorder, any differences we may find may not be due to factors related to the illness.
Do I need to prepare for the study?
Some of the procedures will require that you be reasonably rested and alert, so sleeping late or consuming large amounts of alcohol the night before might not be a good idea. If you visit us, remember to bring your glasses or contact lenses if your eyesight is poor. If we visit you at your home, we will need to use a quiet room with a desk or a table (or two quiet rooms with a desk or a table if your co-twin is seen at the same time). You may need to have your phone in a silent mode, or ask a member of your family to attend to phone-calls and bell-rings.
What happens after the study?
We will keep you informed of our findings through our newsletter. We may also contact you from time to time to update your contact details, or ask you if you would like to participate in a new component of the study that was not available when you took part.
What happens if I cannot take part in the study?
The information you have provided will remain confidential. If you have completed both interviews with us, we will offer you a small monetary compensation for your time. We will also ask you if you would be interested in taking part in other research projects that may be more suitable. If yes, we will ask for your permission to disclose your contact details to fellow researchers.
I and my co-twin have read the information and wish to participate. What next?
Please, contact a member of our team (Anna Georgiades on 0207 848 0023/ ) or email us on and do let us know.
There are still things I need to clarify before I make up my mind.
You can contact us on the number above or visit www.iop.kcl.ac.uk/twinstudy
We hope to hear from you!
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